Chimney cooler for air circuit breakers



June 21, 1960 v. A. MoRTENsoN E'r AL 2,942,086

CHIMNEY COOLER FOR AIR CIRCUIT BREAKERS 2 Sheets-Sheet 2 \/2 l if V. A.MORTENSON ETAL CHIMNEY COOLER FOR AIR CIRCUIT BREAKERS lhnq-Q lll June21, 1960 Filed March 6, 1957 United States Patent O CHIMNEY COOLER FoRAIR CIRCUIT BREAKERS Victor A. Mortenson, Scituate, and Donald E.Weston,

Brookline, Mass., assignors to Allis-Chalmers Manufacturing Company,Milwaukee, Wis.

Filed Mar. 6, 1957, Ser. No. 644,251

3 Claims. (Cl. 20o-147) This invention relates tocircuit interruptingdevices and more particularly to means for reducing the amount ofionized gas discharge above the arc chute of a circuit breakerstructure.

In the construction and operation of circuit breaker structures, it isfrequently necessary to provide means for extinguishing quickly the arewhich is drawn between separable arcing contacts. This arc is usuallyblown by blowout means, such as a magnetic blowout coil or an air blast,into an arc chute which is arranged to quench the arc by lengthening it,cooling it, or Aa combination of both.

Arc chutes having spaced insulating plates to lengthen the arc orsqueeze the arc into narrow slots have been used to rapidly increase thearc voltage, decrease the arc current and greatly improve the powerfactor, thereby facilitating interruption of the are at a naturalor'forced current zero. However, it has been found in many cases thatthe arc voltage developed by the arc chute was not the most favorablefor interrupting the power circuit.

The arc chute for an electromagneitc type of circuit breaker is designedto perform two functions, namely, to interrupt a power circuit and toenclose the arc products. As a circuit interrupting device the arc chuteof the magnetic breaker must be capable of controlling the arc voltage,the arc current, the arc energy, the rate of rise of recovery voltageand the phase relationship between arc current and line voltage at theinstant of interruption. As an enclosing structure for cooling anddeionizing the arc products, the arc chute of the magnetic breaker mustprotect all the surrounding operating parts from the effects of the arcor its arc products. All of the gases exhausted from the arc chute mustbe rendered harmless before being exposed to any of the surroundingcircuit breaker `structure or allied equipment. In many cases, however,the gases exhausted from the arc chute remained ionized and caused avisible discharge, such as flame emission, at chute structure. t

Therefore, in accordance with the invention claimed a new and improvedarc interrupting device is provided which cools the gases exhausted fromthe interrupting device within the arc chute enclosure before finaldischarge of the gases to atmosphere, thereby eliminating orsubstantially reducing ionized gas discharge or llame emission fromabove the arc chute of the interrupting device. The arc chute comprisesa plurality of spaced insulating plates arranged to extendlongitudinally of the axis of the arc chute at the arc receiving endthereof, a pair of spaced arc runners, one of said arc runners beingarranged adjacent each of the contacts for providing a conductive pathfor the terminals of the arc from the contacts into the arc chute, anda-plurality of spaced cooling elements arranged above the arc runnersand spaced from the insulating plates at the exhaust end of the arcchute for deionizing the arc products.

It is, therefore, one object of the present invention to vprovide a newand improved arc interrupting device in the exhaust end of the arc icewhich reduction of ionization and visible discharge at the exhaust endof the arc chute is accomplished by cooling the arc products and gaseswithin the arc chute enclosure before discharge to atmosphere.

Another object of this invention is to provide a new and improved arcinterrupting device in which arc discharge cooling means function tocool the arc products and gases without offering a pneumatic impedanceto their flow.

A further object of this invention is to provide a new and improved areinterrupting device in which cooling elements are arranged in apredetermined manner above the arc runners in the exhaust end of an arcchute structure to reduce ionization and visible discharge therefrom.

A still further object of this invention is to provide a new andimproved arc interrupting device in which arc Adischarge cooling meansarranged in a chimney vent above the .arc runners at the exhaust end ofthe arc chute are staggered and insulatingly separated from each other.

A still further object of this invention is to provide a new andimproved arc interrupting device in which are discharge cooling meansare arranged downstream of the arc runners and across the exhaust endofthe arc chute structure.

Objects and advantages other than those above set forth will be apparentfrom the following description when read in connection with theaccompanying drawings, in which:

Fig. 1 is a view in cross section of a magnetic blowout type circuitbreaker employing the present invention;

Fig. 2 is a partial, cross sectional view of a modification of thecooling element arrangement illustrated in Fig. 1;

Fig. 3 is an end view ofthe structure illustrated in Fig. 2 with the arcchute end plate removed;

Fig. 4 is a plan view of the structure illustrated in Fig. 2;

Fig. 5 is an enlarged perspective view of the cooling elements arrangedabove the arc runners shown in Fig. l; and

Fig. 6 is a partial cross sectional view of a modification of the arcrunner cooling element arrangement illustrated in Figs. 2, 3 and 4.

Referring more particularly to the drawings by characters of reference,Fig. 1 illustrates a magnetic blowout type of circuit breaker includingas elements thereof a pair of terminal studs 6 and 7 for connecting thecircuit breaker to line conductors (not shown). Although in general,circuit breakers of the type considered in Fig. l are provided with aplurality of similar pole structures, one for each phase of a polyphaseelectric circuit, only one such pole structure is shown in the drawingsand the circuit breaker will be described in detail as if it was ofthesingle pole type.

The circuit interrupter or breaker in Fig. 1 comprises essentially meansfor opening the circuit to form .the interrupting arc and an arcextinguishing structure. Specically the circuit opening means comprisesa fixed current carrying contact 8, a tertiary contact 9, a fixed arcingcontact 10, and a movable arcing contact 11. Arcing contact 11 ismounted on a contact arm 12 which is pivyotally mounted'at 13 on anextension 14 of the circuit `breaker stud 6 and is operated by means ofa reciprocally movable rod 15. The operating rod 15 is suitablyconnected to an actuating mechanism (not shown) for operating themovable contact between closed and open circuit positions. Fig. 1illustrates the movable contact 11 in closed positon. The arcingcontacts are electrically connected to the lower ends of terminal studs6 and 7. Accordingly, when the breaker is connected in series in a powercircuit and the arcing contacts are separated, an arc amigos@ may beinitiated across the gap formed between the contacts.

For interrupting this power are, an arc extinguishing structure, such asan larc chutel, may be .mounted so lasV to receive the power arc whichis underl theliniuence of thefrnagneticfblowout means.. 'The` arcchutefspreferably isdisposed directly about andabovethelarcing contacts,asshown, lwhen the blowout means act upward, 'but may be mountedin anyothersuitablelocation when the blowout means act inv other directions.Theiswitch orarcing contacts andthe magnetic blowout' structure canassume any preferred form so that a brief description thereof willbelsufficient. The magnetic blowout'-means may comprise a core 17,-poles 18 and a coil 19..which fis electrically connected :totheterminal'r stud. 7 andto fa metallic arc runner 20 so that therar'ccurrent (as "the arc travels along therunner) flows through the blowoutcoil inamanner wellknown inthe art.l f I v Normally the-current iscarried in `the closed circuit position -of the breaker by the springbiasedcontact. `'As lthemovablc arcingl contact 11 is Vactuated to opencircuit position, current is shunted from fixed contact '8 viirst toVtixed `contact 9 and afterwards to fixed arcing -contact"'10. As 'thearc is drawn by the movable arcing contact '11, the larc terminal ofarcing contact 10 is transferred `to larcrunner 20, which is usually anextension arm of the fixed arcing contact 10. As the movable arc-'ing"conta'ct `11 'approaches or reaches its full..opening istroke`thearc .terminal transfers troml the movable arcing contact =1-1 toanarc runner 21iwhich directsthefarcvin the arc chute 16. The arcingcontact 10 and thelzarc "runner 20 are electrically connected 'in:series with :the

' blowout-coilf19 and stud v7. Accordingly, the v-bl'ovvout coil'isalreadyenergized at the inception of the 'arc to finuence the arc in awell known manner, i.e. to drive it in the arc chute 16 in an expandingloop. It willbeap- .parent to one skilled in the art that the blowouttieldcan be utilized in the'most eicient manner by disposingthesiren-poles l18 so as to-cooperate with the blowout coil in theconventional manner outside of the arc chute.

*Arc chute 416 is'provided with af-plurality of slotted jacentfthe` zone'ofi arc initiation to Y-form Tan"y arc passage.

yAsfwellV known'in the'ait the slots maybe arranged'in A4staggeredrelation-'at their downstream ends.vr Thisfout of'registryror staggeredrelationship ofthe slots' causes theformation of azigzag shaped arcpath. Barrierfplates k22'may be provided in some applications of thisinvention with alpluralityrof apertures or perforations which may bearranged to extend from the downstream ends of Vslots'23' toward theexhaust end of the arc chute.

Chimney vents 24 and 25 are arranged at each end'or :sidevof thestack-'of barrier plates 22 above arc runners Z0 and 21. lThese ventsdirect the arc products and gases created'by the arc terminals movingalongA the arc runners-out of the are chute to atmosphere. The extent'ofthe ionization of the gas and the volumeofthe 'arcproductsv produced bythe actionfof the'arclon the arc runners varies 'directly with theamount 'of-current being interrupted and the voltagefcharacteristicsofthe interrupter. It is recognized that the arc products may interferewith the action of the barrier plate stack. Consequently chimney vents24 and 25 are separatedfrom the barrierplate stack and discharge thegases and arc prod- )ucts from the arc runners directly Ato atmospherewithout going through the barriergplate stack. As noted from Vthe"drawings the arc runners direct the terminals of the Aarc into'thechimney vents. i v Y f "A "The chimney' vents while accomplishing theirpurpose fof `separating the'arc products of thev arc runners from thebarrierplate stack produce a concentrationof theseproducts downstream ofthe arcrunners. It has been found that these arc products from thechimney vents are the chief cause of dielectric difficulties outside ofthe confines of the breaker. Since the arc products from the arc runnersare discharged. froma live terminal, this terminal is in effectextendeditothe full distance the produetsaraverfwhil-e an ionizedcondition. If fno; insulation is .present to isolate the terminals, theterminals will dischargetogrounm YForfl'iigl'r current .interruptionthis means that the circuit breaker enclosure 'must blewell insulated orthat the'distances between the ionized 'gas dischargeffron?:"the'l"chimney vents.=.and-a'r1y grounded structure besuflicienttoassure that ionized arc products do not touch groundedmetal.

It has been noted that the arc within the breaker structure will nottravel beyond the height of the barrier plate stacks.'v Thereforeyfitispossible:pneumatically to place metalliccooling:elements 'inf-closevproximityto and down- :streams/of.: the` :tops of :the arcrunnersxwithout the arc terminals jumping from one cooling elementv toanother. 4Eventhoughrtheipotentialio the arcrunner is impressed 'to thedistance the gases remain ionized withinthe chim- ,ueyz vent,nevertheless-beyond the arcirunner the dielec- 'tricstrengthofsrtheaircolumn is increased proportionally `to the :condition of the gas `orairy within the breaker structure and laterrto `thermixt'ureofgas andair between .the arc chutezstructure Ior chimney .vents and theygrounded .enclosurer' :Thecurrentfinterrupting-limitation of thelbreaker structurethereforafis.: that -amount of'current frequiredto;causeuionizedgases .tozextend from the-chim- 'neyrventsto'theegroundedcircuit'breaker enclosure and vcausean. arcdischarge togroundto occur.

In order `to increase the interrupting ability of air typ circuit:brealcenstructures the arc .chutesy in accordancerwithxthe'inventionclaimed are `provided with apluralityofucoolingelemeirts,which, for example, may-be'metal- .lic .ornonmetallic tubular members 30, arranged Iabove *they 4arci runnersz201and 21 yandspaced from the 'barrier .platesiZznat the4 exhaust `endof-thearc chute. lf so de- 'sired,.*these,cooling .-elementsfmay besolid or hollow 'tubulan'niembers oxamaterial having a high specic heat-value.'z.whenf.chirnney vents are: employed above the arc "runnersfasAshown inFigs. Al and 2 of the drawings,'thecoolingelementsf1are,arranged ,to extend from andlare'supportechby.the insulating vmembers 34 forming the .asides`ofzthez:chimney:ventsA and vare arranged transversely :to thelongitudinal; axis-ofthe iarc chute. --'Becausey of Ltherectangular.'`shape*offtheusualchimney vent the longitudinali axis vof; the cooling*elements* extends sub- 'stantiallys.parallel,- with 'the V'short Vaxisofl the vent,n how- 'evergit isrintended'to be .withirr'the scope ofthis invention to f'providefzcooling elements of fany suitable vcrosssec- -"tionalfiformarrangedto extend in 'any desirable direction withinthe chimney structure. n most applications the rcoolirigsurfaces` ofutheVelements Y`are :so arranged that l.they 'oir'er'the'rlestiamountofpneumatic impedance to theoW-of gases and arcproducts through thechimney -ventsuxForxthis reason and* for the further reason Athat"the-.voltage vof the Y'arc-'runner is impressed onlyv asfarasionization travels-throughfthechimney vents, separate coolingelements30 fare tpositioned' in rows lin lspaced staggeredE'relationship-to-c'ine another, such that, while ostensiblypresentingga-solid'sfront of cooling elements to animee 51 are arrangedin isolated groups to extend transversely to the longitudinal axis ofythe arc chute and to the direction of movement of the arc, arc productsand gases through the arc chute structure. Each group may be separatedor compartmented from the adjacent groups by insulating material 33. Thes ize and number of compartments used in a particular arc chutestructure is determined by the voltage gradient across the arc chute.Each group of tubes is exposed to and reacts on only a portion of thevoltage across the arcing contacts or arc runners. i

Compartmentization of the arc chute structure assures that each group oftubes or cooling elements functions to its fullest capacity by coolingonly a certain portion of the generated gas and arc products. The numberof tubes used and their geometrical arrangement within the arc chuteenclosure is determined by the amount of cooling required and theparticular position and amount of discharge volume of arc products andgases from the barrier plate stack. Tubes 31 are staggered in such a.manner that the space between them provides full discharge of the arcproducts and gases from the arc chute structure at the same time beingso arranged that the are products and gases discharged from the barrier`plate stack must pass adjacent to -the cooling elements 31 before beingdischarged to atmosphere. In this manner cooling is accomplished withoutrestriction to the normal flow of gases or arc products. Y

The group of cooling elements arranged adjacent each end of the arcchute barrier plates comprises a greater number of cooling elementswhich extend farther downstream from the arcing contacts than do theelements of the groups arranged intermediate the ends of the arc chutestructure. This arrangement provides a larger number of cooling elementsimmediately above the zones of the greatest arc product and gasdischarge production from lthe barrier plate stack, namely, above theareas adjacent the ends of the arc chute structure and near` the zonesof the are runners than do the groups intermediate the ends of the arcchute structure.

`If so desired the respective groups of cooling elements 31 may bearranged in removable or detachable compartments which can betemporarily arranged in a given position in the arc chute structure andlater moved to another more eiective position. The tubes of eachcompartment are arranged in a plurality of rows wherein each coolingelement of each row is arranged in staggered relationship to tbeelements of adjacent rows. At least some of the cooling elements in atleast one of the groups may be composed of insulating material. In theremovable compartment structures the walls of Athe compartments are madeof insulating material of the type capable of withstanding the heat ofthe arc products and gases.

The cooling elements 36 and 31 are arranged as after coolers in theexhaust end of the arc chute structure and are spaced a predetermineddistance downstream from the arc runners and the barrier plates. Theseelements or tubes function -to cool the arc products or gases withoutoiering a pneumatic impedance to their flow. In other words, theperformance of the barrier plate stack is not affected by pneumaticblocking and the full arc interrupting ability of the barrier platestack is developed.

Fig. 2 illustrates an enlarged partial cross sectional View of amodification of the arc chute structure shown in Fig. l wherein theinsulating tubes 31 are arranged in similar groups across substantiallythe full length of the exhaust end of the arc chute structure. Fig. 3 isan end view of Fig. 2 with the arc chute end plates removed wherein theparticularly geometrical arrangement of the cooling elements 30 isevident. lFig. 4 illustrates a plan view of Fig. 2 showing the manner-in which the cooling elements or tubes extend across the exhaust endsof the barrier plates 22.

Fig. 5 is a perspective View of the cooling elements 30 Shown rin Fig. lbut illustrates one way of fastening the tubes to a wall of the chimneystructure.. As noted from Fig. 5 the chimney vent and cooling elementsmay be separately assembled and detachably connected to the circuitbreaker structure.

Fig. 6 illustrates a further modification of the cooling element chimneyvent arrangement shown in Figs. l to 5, inclusive, wherein the coolingelements 30 extend part way .finto and are firmly held by the side wallsof the chimney structure.

Although but a few embodiments of the present invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdepart-A fing from the spirit of the invention or from the scope oftheappended claims.

What lis claimed is:

1. An electric circuit interrupter comprising a pair of relativelymovable contacts, means for drawing an arc between said contacts, an arcchute for receiving the arc at one end thereof and exhausting the arcproducts at the other end, said arc chute comprising a plurality ofspaced insulating plates arranged to extend longitudinally of Ithe axisof said chute at the arc receiving end thereof, a chimney vent arrangedadjacent said plates outside of said chute, an arc runner arrangedadjacent one of said contacts for providing a conductive path for theterminal of the arc from said one of said contacts into said vent, aplurality of spaced tubular cooling elements arranged to extendtransversely to the longitudinal axis of said chute above said runnerand within said vent, and a plurality of groups of spaced tubularcooling elements arranged adjacent said plates at the exhaust end ofsaid chute, said groups of said cooling elements being arrangedtransversely to said plurality of spaced tubular cooling elements, saidcooling elements in said vent and adjacent said plates cooling anddeionizing the gases and arc products occurring during circuitinterruption.

2. An electric circuit interrupter comprising a pair of relativelymovable contacts, means for drawing an arc between said contacts, an arcchute for receiving the arc at one end thereof and exhausting the arcproducts at the other end, said arc chute comprising a plurality ofspaced insulating plates arranged to extend longitudinally of the axisof said chute at the arc receiving end thereof, a pair of chimney ventsarranged adjacent said plates outside of said chute, a pair of spaced-arc runners, one Vof said runners being arranged adjacent each of saidcontacts for providing a conductive path for the terminals of the arcfrom said contacts into each of said vents, a plurality of spacedtubular cooling elements arranged to extend transversely to thelongitudinal axisy of said chute above said runners and within saidvents, and a plurality of groups of spaced tubular cooling elementsarranged adjacent said plates at the exhaust end of said chute, saidcooling elements of said groups being arranged substantially ninetydegrees out of phase with said plurality of spaced tubular coolingelements, said cooling elements in said vents and adjacent said platescooling and deionizing the gases and arc products occurring duringcircuit interruption.

3. An electric circuit interrupter comprising a pair of relativelymovable contacts, means for drawing an arc between said contacts, an arcchute for receiving the arc at one end thereof and exhausting the arcproducts at the other end, said arc chute comprising a plurality ofspaced insulating plates arranged to extend longitudinally of the axisof said chute at the arc receiving end thereof, a pair of chimney ventsarranged adjacent said plates outside of said chute, a pair of spacedarc runners, one of said runners being arranged adjacent each of saidcontacts for providing a conductive path for the terminals of the arcfrom said contacts into each of said vents, a plurality of spacedtubular cooling elements arranged to extend transversely to thelongitudinal axis of said chute above said runners and within saidvents, a plurality of groups of' spaced metallic tubular coolingelements arranged adjacent saidfplate's at the exhaust end of saidchute, said cooling elements of 'said groups being arrangedsubstantially ninety degrees out of phase with said 'plurality ofspaczedtnlula'r coolingelex'ne'nts, and insulating 5 means Aajrra'ngedbetween each of said groups 'of said elements for isolating said'groupsof elements from each other, said grops of elements adjacent eachyside portion of said chute comprising a greater number of said eleiments than lsaid groups intermediate `the side portions of `10 saidchute.

References Citedin thefile of this patent UNITED `STATES"PATENTS p1,916,418

crago Jiny 4, 1933 15 8 yClerc f` Dec. 18, 1934 Prince Allg. V1941-2Linde Aug. 18, 19212 Healis Dec. S, 1942 Bardem Feb. 9, 1943 Walle Dec.28, 1943 Sc'Ott July 27, 1948 R'idgley June 23, 1953 Taylor Mar. 13,1956 FOREIGN PATENTS Great vBritain Mar. 19, 1931 GreatBritan Sept. 8,1954 Great Britain Dec. 1'2, 1956

